The invention generally relates to thermal upgrading of carbonaceous materials, such as sub-bituminous rank and lignite rank coals, peat and various forms of bio-mass fuels. More particularly, the invention concerns thermal upgrading of carbonaceous materials by direct contact with a heating medium and by removing moisture from the charge as hot water.
U.S. Pat. No. 5,071,447 to Koppelman discloses methods and apparatus for steam treating carbonaceous materials. Under the system disclosed in the '447 patent, steam is injected at the top of a processing vessel.
U.S. Pat. No. 5,769,908 to Koppelman relates to the treatment of carbonaceous materials by injecting an inert gas into the carbonaceous material under a vacuum or injecting steam into the carbonaceous material either with or without the vacuum being applied in a controlled manner to more consistently treat the charge of carbonaceous material.
While the prior teachings in the two above cited Koppelman patents are believed to have been advances in the art addressing many problems in the area of thermal upgrading of materials, such as coal, there remains a need in the art to more consistently insure that all surfaces of the charge of carbonaceous material reach the same final temperature, to minimize free moisture accompanying the upgraded charge, and to accomplish improved removal of unwanted byproducts from the charge.